FIELD OF THE INVENTION
The invention relates to a method for etching damaged zones or destruction zones on an edge of a semiconductor substrate with a resist-free semiconductor substrate front side and a resist-free semiconductor substrate back side. The invention also relates to an etching system suitable for the etching process.
When silicon wafers are produced, the wafer edges are ground, to put them into a suitable form. These grinding processes create imperfections in the crystal, which in the ensuing machining processes can propagate from the edge toward regions which will be rendered active at a later point. This generally causes damage to or failure of the corresponding components.
Two processes have essentially been known in the art for eliminating these types of damage zones or imperfections. In one such process, the wafer edges are mechanically repolished. However, the imperfections that are located at a deeper level cannot be eliminated thereby. In the second process, the wafer is exposed to wet-chemical overetching, known as chemical polishing. However, the front side and back side of the semiconductor substrate must not also be removed, because that would impair the homogeneity of wafer thickness. The front and back sides of the semiconductor substrate are therefore suitably protected, and in particular they are coated with resist. These resist coatings account for high chemical consumption.